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arm64: split counter validation function 

In order for the counter validation function to be reused, split
validate_cpu_freq_invariance_counters() into:
 - freq_counters_valid(cpu) - check cpu for valid cycle counters
 - freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate) -
   generic function that sets the normalization ratio used by
   topology_scale_freq_tick()

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201106125334.21570-3-ionela.voinescu@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ionela Voinescu 2020-11-06 12:53:33 +00:00 committed by Catalin Marinas
parent 4b9cf23c17
commit bc3b6562a1
1 changed files with 26 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
arch/arm64/kernel/topology.c
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@ -145,45 +145,49 @@ void update_freq_counters_refs(void)
this_cpu_write(arch_const_cycles_prev, read_constcnt());
}
static int validate_cpu_freq_invariance_counters(int cpu)
static inline bool freq_counters_valid(int cpu)
{
u64 max_freq_hz, ratio;
if (!cpu_has_amu_feat(cpu)) {
pr_debug("CPU%d: counters are not supported.\n", cpu);
return -EINVAL;
return false;
}
if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
!per_cpu(arch_core_cycles_prev, cpu))) {
pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
return -EINVAL;
return false;
}
/* Convert maximum frequency from KHz to Hz and validate */
max_freq_hz = cpufreq_get_hw_max_freq(cpu) * 1000;
if (unlikely(!max_freq_hz)) {
pr_debug("CPU%d: invalid maximum frequency.\n", cpu);
return true;
}
static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
{
u64 ratio;
if (unlikely(!max_rate || !ref_rate)) {
pr_debug("CPU%d: invalid maximum or reference frequency.\n",
cpu);
return -EINVAL;
}
/*
* Pre-compute the fixed ratio between the frequency of the constant
* counter and the maximum frequency of the CPU.
* reference counter and the maximum frequency of the CPU.
*
* const_freq
* arch_max_freq_scale = ---------------- * SCHED_CAPACITY_SCALE²
* cpuinfo_max_freq
* ref_rate
* arch_max_freq_scale = ---------- * SCHED_CAPACITY_SCALE²
* max_rate
*
* We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
* in order to ensure a good resolution for arch_max_freq_scale for
* very low arch timer frequencies (down to the KHz range which should
* very low reference frequencies (down to the KHz range which should
* be unlikely).
*/
ratio = (u64)arch_timer_get_rate() << (2 * SCHED_CAPACITY_SHIFT);
ratio = div64_u64(ratio, max_freq_hz);
ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT);
ratio = div64_u64(ratio, max_rate);
if (!ratio) {
WARN_ONCE(1, "System timer frequency too low.\n");
WARN_ONCE(1, "Reference frequency too low.\n");
return -EINVAL;
}
@ -230,8 +234,12 @@ static int __init init_amu_fie(void)
}
for_each_present_cpu(cpu) {
if (validate_cpu_freq_invariance_counters(cpu))
if (!freq_counters_valid(cpu) ||
freq_inv_set_max_ratio(cpu,
cpufreq_get_hw_max_freq(cpu) * 1000,
arch_timer_get_rate()))
continue;
cpumask_set_cpu(cpu, valid_cpus);
have_policy |= enable_policy_freq_counters(cpu, valid_cpus);
}